The most popular day to get hitched in that eight-year period was November 10, 2012 – or 10/11/12 – according to a Fairfax Media analysis of Australian Bureau of Statistics data. The next most popular days were November 11, 2011 (11/11/11) and October 10, 2010 (10/10/10).

The trend becomes more obvious when we break down the data by days of the week. Days of the week matter because most couples (58 per cent) marry on Saturdays and very few marry on Tuesdays, Wednesdays or Thursdays. (No one likes a weekday hangover.)

Notice anything about the peak dates?

Most of the peak dates form repeating or sequential number patterns.

The same trend emerges when we look at dates that were unusually popularfor the time of year or day of the week.

July, for example, is the least popular month to marry, thanks to being in the dead of winter. But nearly 1700 couples tied the knot on July 7, 2007 (07/07/07) – nine times the average for a July day.

"It comes down to survival," according to Jess Nithianantharajah, head of synapse biology and cognition at the Florey Institute of Neuroscience and Mental Health.

Our brains are constantly working to make sense of the information flooding in every moment of the day. Recognising patterns is critical to our ability to learn from past experiences and anticipate challenges, Dr Nithianantharajah said.

"Your brain is wired to want to form associations and then complete the pattern … It's what we do for any kind of information in the world," she said.

However, the constant search for connections often leads the brain to see meaning in random patterns – a cognitive error called apophenia.

One of the most well-known examples of apophenia​ is the gambler's fallacy: wrongly believing that after tossing heads 10 times in a row, the probability of tossing heads again is no longer 50 per cent. Pareidolia​ is a visual form of apophenia, such as when people believe they see Jesus' face in a piece of burnt toast. (Don't worry, scientists say it's perfectly normal.)

Superstition, including numerology – the belief that numbers have special meaning – is a kind of apophenia that helps humans to deal with uncertainty, according to psychologists.

"Often we do not, or cannot, know all the facts needed to predict the desirable outcome, so we naturally look for hints and heuristics that would help us make that decision," said The University of Sydney psychologist Sabina Kleitman.

Auspicious dates and "lucky" numbers are a way of trying to guarantee the outcome we want, particularly when a lot is at stake, she said, such as in the case of a marriage.

Ironically for humans, however, (at least, the marrying type) it also means the most "special" dates we choose for this cherished life event are often also the most common.